import * as ethUtil from 'ethereumjs-util'; import * as request from 'request-promise-native'; import {constants} from './constants'; export class RPC { private host: string; private port: number; private id: number; constructor() { this.host = constants.RPC_HOST; this.port = constants.RPC_PORT; this.id = 0; } public async takeSnapshotAsync(): Promise { const method = 'evm_snapshot'; const params: any[] = []; const payload = this.toPayload(method, params); const snapshotIdHex = await this.sendAsync(payload); const snapshotId = ethUtil.bufferToInt(ethUtil.toBuffer(snapshotIdHex)); return snapshotId; } public async revertSnapshotAsync(snapshotId: number): Promise { const method = 'evm_revert'; const params = [snapshotId]; const payload = this.toPayload(method, params); const didRevert = await this.sendAsync(payload); return didRevert; } private toPayload(method: string, params: any[] = []): string { const payload = JSON.stringify({ id: this.id, method, params, }); this.id += 1; return payload; } private async sendAsync(payload: string): Promise { const opts = { method: 'POST', uri: `http://${this.host}:${this.port}`, body: payload, }; const bodyString = await request(opts); const body = JSON.parse(bodyString); return body.result; } }